1. Create complete ladder logic for the state diagram shown in Figure 1. The push buttons START and STOP are normally open
2. Create all the ladder logic for the following state diagram. Make sure to create the code for the system reset. A, B, and C are normally open push button switches and Motion Sensor is an input sensor which could detect the motion of an object. The transitions occur when A, B, or C is pushed or the motion Sensor detects 10 objects. Push button B has the highest priority. It means that if the system is in state-1 and B and C are simultaneously pressed the system will change to the idle state and not to State 2.
3. Consider the following statement:
A motor for a process cannot be started unless, it is clear to start, and both push buttons Right and Left are held down. If the motor is started then the Horn/Siren is turned on to warn people while it is running. If the system is clear to start then the Green Led is on. Once the motor starts the system stops running as soon as one of the buttons (left or right) is released. Until both buttons are released the system is not clear to start again, and the RED Led is on. As soon as both buttons are released at the same time the system is clear to start again. Furthermore, once in the Not Clear Yet state pushing both buttons down again will not restart the motor. The system must be cleared first by releasing both buttons.
The state diagram for the problem described above.
INPUTS
LeftButton -- Normally Open/Up
RightButton-- Normally Open/Up
OUTPUTS
Green LED (default off)
Red LED (default off)
Motor (default off)
Horn/Siren (default off)
4. Consider the system for opening /closing shutter for controlling car entry in a /shed. When a car approaches, the shutter automatically opens; and in five seconds after the car passes the gate, the shutter closes.
The following is the operation flow:
- When a car enters, the arrival detection sensor is turned on.
- The normal rotation motor of the shutter is turned on.
- The shutter reaches the upper limit in six seconds, the upper limit SW is turned on, and the shutter is opened.
- When the car passes the gate, the arrival detection sensor is turned off.
- In five seconds, the reverse rotation motor is turned on.
- In six seconds, the shutter reaches the lower limit, the lower limit SW is turned on, and the shutter is closed.
a) Define the inputs and outputs of the system described above.
b) Describe the process control using state diagrams. You are required to clearly express each state of the system and describe the conditions for state-transitions.
c) Create complete ladder logic for the modified system